When a wave propagating through a medium encounters a change in medium , then which of the following property remains same ?

Options

A. Speed
B. Amplitude
C. Frequency
D. Wavelength

Answer

To solve the question regarding which property of a wave remains the same when it encounters a change in medium, we can analyze the properties of waves as they propagate through different media.

### Step-by-Step Solution:

1. **Understanding Wave Properties**:
- Waves have several properties, including speed, frequency, wavelength, and amplitude. When a wave travels from one medium to another, some of these properties may change.

2. **Speed of the Wave**:
- The speed of a wave is determined by the medium through which it is traveling. When a wave moves from one medium to another (e.g., from air to water), the speed of the wave changes due to the different densities and elastic properties of the media. Thus, speed does not remain the same.

3. **Frequency of the Wave**:
- The frequency of a wave is determined by the source of the wave. When a wave transitions from one medium to another, its frequency remains constant. This is because the frequency is a property of the source that generates the wave and does not change when the wave enters a different medium.

4. **Wavelength of the Wave**:
- The wavelength of a wave is related to its speed and frequency by the equation \( v = f \lambda \) (where \( v \) is the speed, \( f \) is the frequency, and \( \lambda \) is the wavelength). Since the speed changes when the wave enters a new medium but the frequency remains constant, the wavelength must also change to maintain the relationship. Therefore, wavelength does not remain the same.

5. **Amplitude of the Wave**:
- The amplitude of a wave can also change when it moves from one medium to another. This change can occur due to reflection and transmission at the boundary between the two media. Thus, amplitude does not remain the same.

6. **Conclusion**:
- After analyzing the properties of the wave, we conclude that the only property that remains constant when a wave encounters a change in medium is **frequency**.

### Final Answer:
The property that remains the same when a wave propagating through a medium encounters a change in medium is **frequency**.

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